Get ready to see a lot more if this kind of thing as this economy continues to tank. Once completely free tools (even those with limited paid offerings) will be offering very basic versions for free and then ease users with more desire for functionality into a paid model. Heck, trackur does it . Why? Because it makes sense and free only goes so far. It's that simple. The latest to join this model is the popular content sharing tool SlideShare. TechCrunch reports SlideShare,